Theoretical Angle Research Articles

The spatial distribution of China's solar energy resources and the optimum tilt angle and power generation potential of PV systems

This study aims at filling the gaps and completing the missing global solar radiation and diffuse solar radiation data considering the limited radiation data of 85 meteorological observation stations and the routine meteorological data of 2001 meteorological observation stations. Employing the Inverse Distance Weighing model, the annual and seasonal spatial distributions of global solar radiation and diffuse solar radiation are obtained. A calculation method of the optimum tilt angle of photovoltaic systems for optimal utilization is established using the Collares-Pereira and Rabl hourly solar radiation model and the solar radiation on sloped surfaces model. The spatial distribution of the optimum tilt angle is obtained using the proposed method. The simplified calculation method of the optimum tilt angle based on latitude and altitude is established by introducing two factors of latitude and altitude. In addition, the annual and seasonal photovoltaic power of China is calculated, and the spatial distribution of China's solar resource utilization potential is obtained using the calculated optimum tilt angle, solar radiation data on sloped surfaces, and the photovoltaic power model. The results show that the annual global solar radiation in China is in the range of 3097–7311 MJm−2, and the annual diffuse solar radiation value ranges from 495 to 3036 MJm−2. Moreover, the optimum tilt angle value in different regions of China is found to range between 14.5°and 49.1°, and the theoretical optimum tilt angle value generally aligns with the law of angle increasing with latitude. The annual photovoltaic power generation is between 117 kWhm−2 and 483 kWhm−2. Compared with the solar energy utilization potential of a PV placed on the horizontal surface, the annual average power generation of a PV panel placed at the optimum tilt angle can increase by up to 144.76 kWhm−2, with an average increase of 10.41%.

Analysis of Rollover Characteristics of a 12 kW Automatic Onion Transplanter to Reduce Stability Hazards

The rollover tendency of upland farm machinery needs to be carefully considered because upland crop fields are typically irregular, and accidents frequently result in injuries and even death to the operators. In this study, the rollover characteristics of an underdeveloped 12 kW automatic onion transplanter were determined theoretically and evaluated through simulation and validation tests considering the mounting position of the transplanting unit and load conditions. The center of gravity (CG) coordinates for different mass distributions, and static and dynamic rollover angles were calculated theoretically. Simulation and validation tests were conducted to assess the static rollover angle under different mounting positions of the transplanting unit and load conditions of the onion transplanter. The dynamic rollover tendency was evaluated by operating the onion transplanter on different surfaces and at different speeds. According to the physical properties and mass of the onion transplanter, the theoretical rollover angle was 34.5°, and the coordinates of the CG gradually moved back to the rear wheel axle after attaching the transplanting part and under upward riding conditions. The average simulated rollover angle was 43.9°. A turning difference of 4.5° was observed between the right and left sides, where a 3° angle difference occurred due to the load variation. During the dynamic stability test, angle variations of 2~4° and 3~6° were recorded for both high and low driving speeds in the vehicle platform and transplanting unit, respectively. The overturning angles also satisfied the ISO standard. This study provides helpful information for ensuring the safety of upland crop machinery operating under rough and sloped field conditions.

Jk-integral applied to mixed-mode fatigue crack propagation and life prediction in metal welding interface

In this paper, an innovative fatigue crack propagation model of metal welding interface is investigated based on the concept of Jk-integral (k = 1, 2) in elastic–plastic material, including the prediction of crack propagation path and life. In order to validate the effectiveness of the present fatigue model, the experiments of mixed-mode interface fatigue cracks are carried out on compact tensile shear specimens of N36 zirconium alloy using DIC methods. The results demonstrate that the fatigue crack only propagates along the interface under mode I loading where the relationship between the crack growth rate da/dN and ΔJ1 (the J1-integral range per loading cycle) is logarithmic linear. As for mode I/II mixed-mode loading, interface cracks start to propagate along the interface when J1 reaches Jint-C (the interface fracture toughness). When Jtotal (the vector sum of J1 and J2) reaches Jsub-C (the substrate fracture toughness), the crack deflects to the substrate in the Jtotal direction. In this case, da/dN shows a two-stage logarithmic linear relation with ΔJtotal (the Jtotal-integral range per loading cycle) under mixed-mode loading, and the critical Jtotal at the beginning of crack deflection is approximately matching the specific value. The theoretical deflection angle (i.e. the Jtotal direction) calculated from the corresponding J1 and J2 at the beginning of crack deflection is wellconsistentwiththe actual deflection angle observed in experiments. Moreover, the model can clearly describe the two-stage process from the crack propagation along the interface to the crack deflection to the substrate under mixed-mode loading. It is concluded that the proposed fatigue model based on Jk-integral can accurately predict the fatigue crack propagation path and lifetime of metal welding interface.

Polarization-dependent metalens with flexible and steerable bifocal spots

Lenses are an important part of modern optical systems. We propose metalenses with bifocal spots, which realizes the beam focusing with controllable intensity ratio and free deflection of the bifocal spots. The metalens consists of an array of titanium dioxide (TiO2) nanopillars, which can provide two different propagation phases for x-linear polarization (XLP) and y-linear polarization (YLP) incidence, respectively. Therefore, by precisely choosing the size of the nanopillars, it is possible to produce two different focal spots for the two orthogonal input polarized light. And the intensity of the two focal points can be adjusted by changing the polarization angle of the incident light. Superimposing the initial phase distribution of the metalens and the phase distribution of the beam deflector metasurface enables multi-dimensional adjustment of the two focal points and realizes the free deflection characteristics of the metalens. The deflection angle of the focal spot is close to the theoretical deflection angle. In addition, multiple superposition can produce more deflection angles or deflect the focus to a two-dimensional plane. The method of controlling the targeting phase of the metalens by superimposing additional phases gives us the ability to fully manipulate the phase and wavefront of the metalens, providing a new idea for the continuous angle change of future optical lenses.

Effects of vividness, information and aesthetic design on the appeal of pay-per-click ads

PurposeFew studies illustrate how contextual effects (e.g. assimilation and contrast) in pay-per-click ad design may impact consumers' attitudes and purchase intention. To fill this research gap, the authors provide theoretical predictions and empirical evidence on how ad design may prompt an assimilation and/or a contrast effect that may influence consumers' attitudes toward the ad and the brand and purchase intention. They also investigate whether the impact of contextual effects on consumers' decisions depends on the level of vividness in the ad.Design/methodology/approachA 2 (vividness: dynamic motion vs. static page) × 2 (information design: assimilation vs. contrast) × 2 (aesthetic design: assimilation vs. contrast) between-subjects experimental design is used to examine the effects of vividness, information design and aesthetic design. Conditional process analysis is used to assess the mediating role of attitudes toward the ad and the brand in the relationship between contextual effects and purchase intention.FindingsFor dynamic ads (i.e. high vividness) but not for static ads (i.e. low vividness), combined information contrast and aesthetic contrast designs generate a more favorable attitude toward the brand and a higher purchase intention than do combined information assimilation and aesthetic assimilation designs. Notably, combined information contrast and aesthetic contrast designs have the strongest effects than any other combination of assimilation and contrast designs of information and aesthetics. Attitudes toward the ad and the brand are significant mediators between contextual factors and intention to purchase.Research limitations/implicationsThe study examines the effectiveness of online ads from a new theoretical angle based on the attributes of pay-per-click ads.Practical implicationsThe results suggest that when advertisers decide to use dynamic ads, they should adopt a contrast design for both the ad information and its aesthetics.Originality/valueThis study fills a research gap in the contextual effects literature, including providing evidence of an underlying process in the relationship between certain contextual effects and purchase intent. It also extends previous findings of assimilation/contrast in information design to aesthetics design and advances the literature on vividness by examining a moderation effect of vividness.

A Complex Character of the Civil War in Yemen: A Perspective from Pakistan

The civil war in Yemen is a puzzling case, involving local, regional and global actors with conflicting motives. Till recent past, Yemen had not been a hotbed for sectarian strife yet, in the milieu of the ‘Gulf War-2003’ followed by the ‘Arab Spring’, the ground realities greatly changed, bringing ‘sectarian divide’ as one of the many dimensions in the conflict. While Iran continues to deny Saudi accusations of its great designs in Middle East, still we need to ascertain the facts by probing the complex interplay between drivers and actors placed at various levels. The study concludes that besides the ‘sectarian divide’, there are other dimensions of the conflict which are grounded on political, social and strategic aspects, directly influenced by the outside players. As a part of the real politick, Iran and Saudi Arabia are striving to have their grip over the Middle East including the Yemen. The study also concludes that the Yemen being its soft underbelly, Saudi Kingdom would not compromise on its stated goals of having direct influence over it, even if it has to pay a heavy cost. The study suggests that to realize a durable peace in the region, Iran and Saudi led coalition should bridge trust deficit, address perception problems and help various factions to resolve their differences by signing a ‘new social contract’. From theoretical angle, this paper adopts a realist line, focusing on security concerns of the state actors.

Xecutive Pay Cuts during Covid: Yielding to Pressure or Potential for Real Change?

Executive compensation has been the subject of longstanding criticisms for possibly setting wrong incentives or for being excessive. In the Covid pandemic in 2020/2021, numerous CEOs worldwide decided to temporarily forgo part of their compensation in response to calls for solidarity with stakeholders who had to make financial or other sacrifices. While there have been suggestions that these concessions might be the starting point for wider reforms of executive compensation to address some of the criticisms, pay has quickly returned to pre-Covid levels and reached new record highs. This article examines whether the executive pay concessions made during Covid should be considered a temporary phenomenon, or whether they might indeed have the potential to start a larger process of reassessing and reforming executive compensation. The analysis explored three angles: First, the cuts to compensation themselves were examined to understand the type of compensation affected and their magnitude. Second, reasons and pressures that led firms to adjust pay during the onset of the crisis were explored, and whether they can be considered temporary or more fundamental. Third, the theoretical angle used legitimacy theory, institutional theory, and resource dependence theory to assess the intention and longevity of measures undertaken. Taken together, the analysis suggests the actions on pay were a temporary reaction to a specific situation, and do not seem to be intended nor contain potential for longer lasting, widespread changes.

Analysis of Anisotropic Steady and Dynamic Seepage of Subsea Tunnels

Although the underwater tunnel is under a rapid development nowadays, the theoretical research methods, including reflection and angle transformation, are still in their infancy. At present, almost all the studies are based on the hypothesis that soil layers are homogeneous, but most of the soil layers are anisotropic in actual soil engineering. Therefore, an analytical derivation method of flow field in heterogeneous media based on the traditional equiangular transformation method is presented. Numerical simulation shows that with the increase of the anisotropic permeability coefficient ratio, the contour line of approximate ellipse becomes flat. On the contrary, the lateral permeability is proportional to the upgrade of the anisotropic permeability coefficient ratio and the permeability appears the same trend.

In-plane resistive anisotropy in Ca2RuO4 measured by rotational square four-point probe method

The resistivity of materials is a fundamental property of solids and is widely used to understand underlying physics as well as to engineer device applications. Conventional four-probe measurement is usually employed to exclude the contributions from parasitic contact resistances. Here, we evaluate the in-plane resistive anisotropy in Ca2RuO4 crystals by using a rotational square four-point probe (4PP) method, which measures an angular dependence of the resistance to precisely detect the resistive anisotropy of materials. A clear sinusoidal dependence of the resistance has been observed, confirming the resistive anisotropy in this system. Finally, the resistance data is fitted with a theoretical angle dependence equation to extract the resistive anisotropy. The observed results are found to be matching with the actual resistivity of the sample.

Striatal connectopic maps link to functional domains across psychiatric disorders

Transdiagnostic approaches to psychiatry have significant potential in overcoming the limitations of conventional diagnostic paradigms. However, while frameworks such as the Research Domain Criteria have garnered significant enthusiasm among researchers and clinicians from a theoretical angle, examples of how such an approach might translate in practice to understand the biological mechanisms underlying complex patterns of behaviors in realistic and heterogeneous populations have been sparse. In a richly phenotyped clinical sample (n = 186) specifically designed to capture the complex nature of heterogeneity and comorbidity within- and between stress- and neurodevelopmental disorders, we use exploratory factor analysis on a wide range of clinical questionnaires to identify four stable functional domains that transcend diagnosis and relate to negative valence, cognition, social functioning and inhibition/arousal before replicating them in an independent dataset (n = 188). We then use connectopic mapping to map inter-individual variation in fine-grained topographical organization of functional connectivity in the striatum—a central hub in motor, cognitive, affective and reward-related brain circuits—and use multivariate machine learning (canonical correlation analysis) to show that these individualized topographic representations predict transdiagnostic functional domains out of sample (r = 0.20, p = 0.026). We propose that investigating psychiatric symptoms across disorders is a promising path to linking them to underlying biology, and can help bridge the gap between neuroscience and clinical psychiatry.

Wettability, Self-Cleaning Property, and Mechanical Durability of A390 Aluminum Alloy with the Major Effect of Si Phases.

Si phases with specific shapes, including primary and eutectic Si phases, were etched on the surface of A390 Al alloy by chemical etching. Meanwhile, their effects on the wettability, self-cleaning properties, and mechanical durability of etched A390 aluminum alloy surfaces were investigated. The results showed that the surface etched for 5 min and modified by 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (FAS-17) demonstrated a contact angle of 153.2 ± 1.4° and a sliding angle of 11.2 ± 1.6°. The theoretical contact angle calculated by constructing a wetting model of Si phases approximates the actual contact angle. Further experiments indicated that the etched surface acquired excellent self-cleaning properties. In addition, the exposed Si phases formed a strong support skeleton, which greatly improved the wear resistance of the hydrophobic surface.

Effects of virtual target size, position, and parallax on vergence-accommodation conflict as estimated by actual gaze

Due to the increased utilization of stereoscopic displays, the scope of the vergence–accommodation conflict has been studied extensively to reveal how the human visual system operates. The purpose of this work was to study the phenomenon of vergence–accommodation conflict by comparing the theoretical eye vergence angle (vergence response) and gaze-based eye vergence angle (vergence stimulus) based on eye tracker gaze data. The results indicated that the gaze-based eye vergence angle was largest at the greatest parallax. The result also revealed that the eye vergence angle accuracy was significantly highest at the nearest parallax. Generally, accuracy improves when virtual objects are put in the middle and close to participants' positions. Moreover, the signed error decreases significantly when the virtual object is in the middle. Based on the results of this study, we can gain a greater understanding of the vergence–accommodation conflict in the stereoscopic environment.

FDEM numerical study on the mechanical characteristics and failure behavior of heterogeneous rock based on the Weibull distribution of mechanical parameters

Rock materials are typically heterogeneous. Traditional digital image processing (DIP) technology and the grain-based model (GBM) method are difficult to apply to engineering-scale problem studies, such as tunnel excavation. Based on the combined finite-discrete element method (FDEM), a random parameter assignment method is proposed to simulate the mechanical properties and failure behavior of heterogeneous rock. The elastic moduli of triangular elements, as well as the strength parameters of quadrilateral joint elements, assigned by this method obey a Weibull distribution. The simulation results of uniaxial compression, triaxial compression and Brazilian disc show that with the increase in the heterogeneity m value, the uniaxial compressive strength, elastic modulus, triaxial compressive strength, equivalent cohesion, equivalent internal friction angle and tensile strength all increase exponentially and approach those of the homogeneous rock sample. In addition, the heterogeneous rock samples mainly shear fail along their corresponding theoretical failure angle under uniaxial and triaxial compression. The simulation results of tunnel excavation indicate that for heterogeneous rock with different m values, the overall fracture morphology of the surrounding rock remains unchanged, and X-shaped conjugate shear failures mainly occur followed by a small amount of tensile failures, which are similar to the homogeneous surrounding rock. However, with the increase in the m value, the failure degree and the maximum fracture propagation range of the surrounding rock decrease exponentially. Moreover, the simulation results of uniaxial compression and tunnel excavation with different element sizes suggest that the random parameter assignment method proposed in this paper is reliable.

The Screening Role of Design Parameters for Service Procurement Auctions in Online Service Outsourcing Platforms

This paper provides a novel theoretical angle and robust empirical evidence demonstrating that the auction duration and the item description length are two essential auction design parameters that can function as screening mechanisms for bidder quality on online service outsourcing platforms. These outsourcing platforms use buyer-determined reverse auctions to find service providers. Using data from a major online outsourcing platform, we examine the effects of the auction duration and the item description length on both bidder entry (i.e., the number of bids and bidder quality) and contract outcomes (i.e., whether a project is contracted and the buyer’s expected utility from the winning bid) based upon the project- and bidder-level analyses. We find that auctions with longer durations and item descriptions attract more bids, but they also attract disproportionately more low-quality bidders, creating a double whammy of higher evaluation costs and adverse selection for buyers. This, in turn, leads to less successful contracting as well as lower buyer utility. Our research highlights the screening role of the auction duration and item description length for buyers on online service outsourcing platforms: by shortening auction durations and item descriptions, buyers can expect higher quality bidders, increase contracting probability, and enhance utility.

Effect of structural conformation of conjugated polymers on spin transport

Organic semiconductors consisting mainly of relatively light chemical elements were expected to exhibit low spin-orbit coupling (SOC) and large spin relaxation time, making them attractive as spin conveyors in spintronic devices. However, a series of theoretical and experimental spin diffusion length and spin Hall angle results contradicting this expectation have triggered an ongoing discussion to understand the coupling of spins to their environment in these systems. In this context we use the prototype material poly(3,4-ethylenedioxythiophene):polystyrene sulfonate as a model conducting polymer system to monitor the impact of chemical doping and the resulting modification of the polymer's backbone conformation on the spin diffusion length. We observed an increase by a factor of 2 of the spin diffusion length during dedoping of the polymer that is accompanied by a respective order of magnitude decrease in the spin Hall angle and the spin admixture parameter indicating a reduction of the SOC strength. This trend is associated with an increased planarity at the dedoped level monitored by Raman spectroscopy revealing that spin transport is inextricably linked to the structural conformation of the organic semiconductor. Spin phenomena of a conjugated polymer can be modified through control of the polymer's structural conformation, paving the way for a new functionality for spintronic based devices.

How to Put the AI in Sustainability - An Empirical Qualitative Study on AI and Sustainability

Both the widespread diffusion of artificial intelligence (AI) and the quest for sustainable development are transforming businesses and society. Businesses are increasingly stepping forward to address grand challenges associated with sustainability, but are faced with complex challenges inside and outside their organizational boundaries. AI appears particularly suited to address these problems as it not only enables businesses to make better predictions but also reduces the costs of predictions. Unfortunately, the intersection of AI and sustainability still exhibits a lack in theory building and empirical investigation. Hence, this study conducted interviews with 21 experts from AI and sustainability to examine the phenomenon, antecedents and effects of utilizing AI for sustainability. As a result, the study presents four themes consisting of patterns that delineate firm activities for managing the use of AI for sustainability. Moreover, it introduces the concept of ambidexterity by demonstrating that the identified activities can be differentiated based on whether they are marked by exploitation, exploration, or ambidexterity. Thus, we contribute to the literature by providing a new theoretical angle to scrutinize AI and sustainability. The findings lay the ground for future quantitative empirical studies and serve practitioners in managing the nexus of the digital and sustainable transformation.

Proportionality and the fight against international tax abuse: comparative analysis of judicial review in EU, international investment and WTO law

ABSTRACT This contribution considers the use of the principle of proportionality to review measures combatting international tax abuse (avoidance and evasion). Our claim is that proportionality, which tends to be viewed as the key analytical tool to balance tax equity against the interests of taxpayers, is ill-suited to the review of such measures. This we will demonstrate from a theoretical angle, but also through the analysis of the CJEU, international investment tribunals and WTO adjudicatory bodies: rather than balancing tax certainty against tax equity or focusing on the efficiency of the anti-tax abuse measures in the pursuit of substantive policy goals (the types of enquires normally associated with proportionality), what we observe is an assessment and gradual demarcation of the rightful territorial extent of the State’s taxation powers.

SUBVERSION OF PRE-DEFINED FEMALE GENDER ROLES IN PAKISTANI SOCIETY: A FEMINIST ANALYSIS OF THE SHADOW OF THE CRESCENT MOON, BUTTERFLY SEASON AND STAINED

The present research aspires to represent the subversion of pre-defined gender roles in the novels; The Shadow of the Crescent Moon (2013) by Fatima Bhutto, Butterfly Season (2014) by Natasha Ahmed, and Stained (2016) by Abda Khan. The researchers had tried to depict the destabilization of gender-based stereotyped identity from the Pakistani perspective. The selected method of study was Feminist Analysis by Tyson (2006), which examined literature as a medium to represent feminist issues, whereas; the theoretical angle of “Matrix of Domination” from Collins’ (2004) Feminist/Gender theory was used as a principle to analyze and depict the subversion of pre-defined gender roles in the selected novels. Present study aimed to establish the notion of gender as a social construct that could be subverted through literary discourses that have the potential to challenge the power-based gender roles within a patriarchal society. In this regard, different critical works of prominent theorists and writers had been discussed briefly in the literature review to project the significance of the works by contemporary Pakistani women writers as a medium to subvert identities formed by their society. Gender was also a means of power, through which the dominant sought to control the subordinate. The objective of the research was to suggest that gender is socially constructed, therefore, it can be deconstructed through literature. The selected novels exemplify the current gender inclinations of today’s Pakistan with the pen of female writers. Stereotyped gender identity is a socially constructed vice that divides humans into segments, hence it is required of the contemporary discourses to decenter such power discourses that perpetuate hegemonic boundaries and restrict the women into social shackles of imposed identities.

Traveler Pro-social Behaviors at Heritage Tourism Sites

This study aimed to explain the development of tourists’ pro-social intentions during heritage tourism within the pandemic context by combining the norm activation model (NAM) and two significant variables in the theory of planned behavior (TPB). The quantitative data analysis results indicated that the proposed hypotheses have been partially supported, which resonated and enriched the existing studies on COVID-19-related pro-social tourism and tourist behaviors from a theoretical angle. Based on the research outcomes, the corresponding managerial implications for heritage tourism practitioners and meaningful references for future researchers to promote sustainable and pro-social heritage tourism products have been discussed.

High bandwidth measurements of auroral Langmuir waves with multiple antennas

Abstract. The High-Bandwidth Auroral Rocket (HIBAR) was launched from Poker Flat, Alaska, on 28 January 2003 at 07:50 UT towards an apogee of 382 km in the nightside aurora. The flight was unique in having three high-frequency (HF) receivers using multiple antennas parallel and perpendicular to the ambient magnetic field, as well as very low-frequency (VLF) receivers using antennas perpendicular to the magnetic field. These receivers observed five short-lived Langmuir wave bursts lasting from 0.1–0.2 s, consisting of a thin plasma line with frequencies in the range of 2470–2610 kHz that had an associated diffuse feature occurring 5–10 kHz above the plasma line. Both of these waves occurred slightly above the local plasma frequency with amplitudes between 1–100 µV m−1. The ratio of the parallel to perpendicular components of the plasma line and diffuse feature were used to determine the angle of propagation of these waves with respect to the background magnetic field. These angles were found to be comparable to the theoretical Z-infinity angle that these waves would resonate at. The VLF receiver detected auroral hiss throughout the flight at 5–10 kHz, a frequency matching the difference between the plasma line and the diffuse feature. A dispersion solver, partially informed with measured electron distributions, and associated frequency- and wavevector-matching conditions were employed to determine if the diffuse features could be generated by a nonlinear wave–wave interaction of the plasma line with the lower-frequency auroral hiss waves/lower-hybrid waves. The results show that this interpretation is plausible.